Optical control plane implementations provide automated setup and control of services. Advantageously, control planes offer multi-vendor and inter-domain inter-working, enhanced service offerings such as Ethernet over SONET/SDH or Optical Transport Network (OTN), end-to-end service activation, cross-domain provisioning of switched connection services, service restoration and the like. Traditionally, creating traffic paths through a series of Network Elements (NEs) has involved configuration of individual cross-connects on each NE. Control planes allow a user to specify the start point, end point, and bandwidth required, and an agent on the Network Elements allocates a path through the network, provisioning the traffic path, setting up cross-connects, and allocating bandwidth from the paths for the user requested service. The actual path that the traffic will take through the network is not specified by the user.
Several control plane standards exist including ITU-T Automatically Switched Optical Network (ASON), IETF Generalized Multi-Protocol Label Switching (G-MPLS) also known as Automatic Switched Transport Network (ASTN), and Optical Internetworking Forum (OIF) User-Network Interface Signaling Specifications (UNI) and Inter-Carrier Network Interface Signaling Specification. ASON specifications generally define an optical control plane communication framework. G-MPLS defines control plane discovery, routing, and signaling protocols. OIF UNI/E-NNI specifications define protocol extensions for multi-vendor interoperability.
In traditional networks, an optical control plane communicates through In-Band (IB) signaling, such as using standard SDH/SONET overheads with proprietary protocols to talk between nodes and discover links and exchange topology information. For customer networks who wish to implement control plane technology in regions that are not, or are only partly, served by cable systems that have wavelength access, i.e. without SDH/SONET overheads, control plane communication cannot be achieved through IB signaling. A data communication network (DCN) can be utilized as a general solution to enable control plane functionality on links that terminate the SDH/SONET overheads and provide signaling, such as Private Network-to-Network Interface (PNNI), at places where the IB communication is not possible. The links that are connected through DCN network are referred to as Out-of-Band (OOB) links; normal links with full transparency are referred to as In-Band (IB) links. The new region may have a mixture of OOB and IB links. Disadvantageously, there is no mechanism that is available today to run a single PNNI protocol on a mixture of network nodes where IB and OOB can work concurrently together.